This invention relates to novel allatostatins which have the potential for regulating the growth of certain insects and may in turn be useful in the area of insect control. Various means of insect control have been achieved over the years, including the use of arsenicals, oils, botanicals, DDT, carbamates and organophosphates. But these insecticides can be highly toxic to vertebrates, in addition to the target insects. Today, a more environmentally acceptable means of insect control is in great demand. Due to the growing awareness of health and ecological considerations, society is increasingly demanding the development of insect-specific control measures that are nonpollutant, safe, and compatible with integrated pest management systems. With increasing appreciation of the physiology and ecology of target and nontarget species, the demand for environmentally acceptable means of insect control can be met.
Insect neuropeptides are involved in the control of a wide range of physiological, biochemical and developmental functions, including water balance, lipid and carbohydrate metabolism, muscle contraction, reproduction, and growth and development. Several neurohormones that regulate homeostasis, metabolism and behavior have been characterized (J. J. Menn and A. B. Borkovec, J. Agric. Food Chem. 37,271 (1989)). In addition, four allatostatic neuropeptides that inhibit juvenile hormone synthesis have been isolated from brains of the virgin female coackroach Diploptera punctata (A. P. Woodhead et al. Proc. Natl. Acad. Sci. USA 86:5997 (1989) and G. E. Pratt et al. BBRC 163:1243 (1989)). This invention discloses new insect allatostatins which have functionally different N-termini.
One insect control strategy is the interference of insect juvenile hormone (JH) synthesis. Maintenance of a particular level of JH in the hemolymph, or change of JH titer as a signal for physiological changes in the insect, both require that the insect must be able to control the overall balance of JH synthesis, JH uptake and release by tissues, and JH clearance by degradation and excretion. In addition, the insect must be able to control the hemolymph volume. Control of JH synthesis is achieved by regulating the endocrine activity of the corpora allata (CA), the identified source of juvenile hormone (R. Feyereisen, in Comprehensive Insect Physiology, Biochemistry and Pharmacology, G. A. Kerkut and L. I. Gilbert, Eds. (Pergamon, Oxford, 1985) Vol. 7, pp. 391-429).
Neuropeptides (also referred to as neurohormones) which regulate the synthesis of JH are generally classified as allatotropins or allatostatins (J. J. Menn and A. B. Borkovec, J. Agric. Food Chem. 37:271 (1989)). The allatotropins are stimulatory substances and the allatostatins are inhibitory substances (R. Ruegg et al., Experientia 39:132 (1983) Woodhead et al and Pratt et al.) The allatostatins of this invention are inhibitory substances which inhibit juvenile hormone synthesis by the corpora allata. By inhibiting the synthesis of juvenile hormones, the normal development, maturation and reproduction of insects can be controlled.